A conventional detector circuit of this type comprises two cascaded capacitors, one of them in series and the other in shunt with a load, connected across the carrier source with interposition of a series diode between the first-mentioned capacitor and the load, the forward resistance of this diode serving as a charging resistance for the shunt capacitor. Another diode is connected between the usually grounded common input and output terminal of the circuit and a junction point formed by the series capacitor with the series diode. One of the half-cycles of the carrier oscillation, i.e. the one (hereinafter assumed to be positive) which passes the series diode, charges the shunt capacitor to a potential somewhat less than the (positive) voltage peak, the difference being due to the forward voltage drop of that diode. Upon the next half-cycle, the junction point between the series capacitor and the series diode is maintained by the shunt diode at a potential somewhat more negative than the reference potential (normally ground), owing to the forward voltage drop of the shunt diode. On the positive-going swing of the carrier oscillation, the voltage V.sub.A at the junction point reaches a value which falls short of the peak-to-peak voltage difference of the input oscillation by a value V.sub.D corresponding to the aforementioned voltage drop.